1) Field of the Invention
This disclosure relates to non-chromium containing coatings for metals. Particularly, the disclosure relates to a no-rinse, non-chromate, non-metal phosphate coating for steel, zinc coated steel, and aluminum surfaces comprising a stabilizing agent to improve the adhesion of siccative, conversion and/or passivation coatings to the surface and provide enhanced corrosion protection.
2) Description of Related Art
A variety of compositions are known for commercial applications to prepare metal surfaces. For example, chromium compounds and heavy metal phosphate conversion coatings are used in commercial applications to prepare metal surfaces prior to painting operations. However, growing concerns exist regarding the toxicity profile of chromium and the pollution effects of chromates, phosphates, and other heavy metals discharged into rivers and waterways from the waste streams of these industrial processes.
Accordingly, there is a need in the art to provide an effective treatment free of chromium compounds or heavy metal phosphates to provide dried in place conversion or passivation coatings to inhibit metal surface corrosion and enhance place conversion or passivation coatings to inhibit metal surface corrosion and enhance the adhesion of paint or other coatings that may be applied to the surface. The U.S. Pat. No. 5,433,976 describes an alkaline solution made from a combination of inorganic silicate or aluminate, an organofunctional silane and a non-functional silane as a treatment for metal that provides enhanced corrosion resistance of painted metal substrates. U.S. Pat. No. 6,106,901 discloses a method to treat a metal with a solution comprised of a ureido silane with one or more multi-silyl-functional silanes. A solvent such as an alcohol may be included to improve the solubility or stability and an acid may be added to adjust the pH of the solution below 7. The solvent may be substantially removed in a subsequent step.